Various documents, notably document U.S. Pat. No. 5,090,256, describe methods of extracting gaseous constituents contained in drilling fluids so as to detect the presence of said constituents in the reservoir rocks crossed through. The measuring principle consists in continuously taking a certain volume of drilling fluid in order to <<degas>> it in a suitable device. The gases extracted from the fluid sample are then transported to a measuring cab located at a distance from the wellhead. The transport line is generally a tube that is several ten meters long. The transported gases are then analysed by chromatography in the cab.
In order to increase the quantification precision and to extend the possibility of carrying out measurements on hydrocarbons, tests have shown that conventional devices are not efficient enough, in particular for hydrocarbon-containing constituents above C4.
The object of the present invention is to provide an analysis device and method allowing to prevent or at least to limit retention, adsorption and absorption phenomena that lead to erroneous qualitative analysis results and make quantification difficult or even impossible, thus causing analysis delay phenomena that can lead to interpretation errors concerning the zones crossed by the borehole. Furthermore, these adsorption and absorption effects can be followed by non-quantifiable salting-out phenomena that make correlation of the measurements performed difficult according to the borehole depth.